My vehicle is pretty tall and I don't have room to get into my garage with a 30" antenna, even on the fender instead of the roof.

I'm looking at one of these and was wondering if they're any good.

Thanks!

I see the local natural gas company using them. Thanks for clearing up my confusion!

73,
John, KF5ZMD

I'm using a Diamond Quad Band with my Yeasu 8900r.

It folds over at that point where my matte black paint job is scraping off.



Some people will say it's too much hassle to get out and fold it over every time you pull in to the garage.

I'd rather make that compromise than crappy transmission and recieve.

I saw one in my (sort of) local HRO, and have done some research on it because I find it intriguing.

I have yet to find anything where someone has actually put it on a real deal analyzer. The commentary online is about as useful as GD discussing a new polymer striker fired pistol.

I read the patent, it is worth reading.

For what its worth, I’m very much into antennas, and much of my study as an electrical engineer has been focused on them and electrical physics. I do think it is an interesting design and in my opinion it should work well. The gain and VSWR numbers posted aren’t unreasonable and I appreciate that the VSWR numbers take into account the surface the antenna is mounted on, because that can change the ratio significantly.

I am planning on buying one for the same reasons the OP is considering one; hopefully next year I will be starting a 4x4 build, and I also have a low garage. It would need to placed in a protected location, I imagine a hit from a tree branch would not be good for it. Since it is on a NMO mount I suppose you could easily remove it if it was about to whack something on the trail.

I am keeping the 1/4 wave 70cm antenna on the trunk of my vehicle for purely economic reasons, otherwise I would have no problem replacing it with the Compactenna.

I really need to spend my next batch of radio dollars on a couple lightning arrestors for my shack, otherwise I might go ahead and grab one of these to start testing it. Maybe after Christmas...

Thanks man!  Let us know how it works, will you?

Well that's what I'm trying to find out - does it have good xmit properties or not?

The reason it's even a question is that it's going on the XYLs vehicle and I can't control if she remembers to bend a hinged antenna over or not.

I certainly will, like I said December/January timeframe most likely.

I have looked at the folding antennas, but I live and work in a city, so there are a lot of obstructions to whack a big antenna on. I use parking garages a lot in addition to my home garage. I am 100% sure I will forget to fold it one day , not even going there with the YL.

Thanks for the link to the patent. Really interesting. It conveniently spells out the dimensions if you wanted to try and build one yourself. Should be relatively simple?

Yep, essentially take a flat rectangular piece of copper sheet of the proper dimensions and roll it with some insulating material to keep proper spacing between layers.  Feed point is attached to the lower/inner corner of the sheet and then placed over top of a ground plane.  Not too complex, might make a fun little project to play around with if you wanted to DIY one.

I had the same thought but upon pricing some material I realized $90 was a good deal for an antenna rugged enough to live on a vehicle.

I would be fun to make one though...

Size matters.  Though... I am impressed with how well the little shark fin antenna receives on the roof of my WK2 for both AM and FM.  But, receiving is easier than transmitting.  Need to see if someone actually tested that antenna against a 1/4 wave, 1/2 wave, etc, to see how it really works.

I drill holes in my roof, use thick metal NMO mounts with fender washers underneath.  The only time I take off my antennas is at the car wash, though.

Ok, now I'm curious how their 75m thru 70cm antenna works... $400 tho.

It would be a lot of fun to put a bunch of popular ham antennas including the ones in question into a range and actually see what they really do. Sadly the only range I even have a prayer of accessing these days is designed for 1 GHz on up.

I shouldn't have watched the dude on Youtube - the antenna may (or may not) work but the guy comes across as a James Bond villain.

The link only shows 4 pages of an 8 page document. I could not see any performance numbers. The "full document" button link doesn't work either.

I'm always very cautious when someone claims that a short antenna can perform as good as a full size, resonant antenna. It almost sounds too good to be true when they claim very wide band performance as it's very difficult to achieve with shortened antennas while maintaining decent efficiency. Some shady "manufacturers" limit their tests to a simple SWR check. LOL.
This doesn't mean that something like this won't work and it could be a good compromise when space is limited.
Also, like you said, the radials or the surface the antenna is mounted on, will significantly affect the antenna's performance. I've seen some designs where the radials radiated more RF than the antenna.

OP,
BTW, a top portion of a vertical antenna can be bent at 90 degrees and still perform quite well. It may not look very nice but it will do the job.
Also, you can get a motorized mount and lower the antenna before you drive into the garage.

Added later: I'm tempted to get one and perform some real life testing. It's a bit pricy though.

Any antenna designed for multiple frequencies and especially multiple bands has compromises. I would not expect something like the compactenna or the little “shark fin”, or those stubby Laird vehicle antennas to outperform a monopole or a dipole.

The antenna on my vehicle now is 2m/70cm that in the manufacturers specs says has 2.5 dB gain for 70cm and unity for 2m. It is ok for repeater use, granted I live on the front range of CO where all of our repeaters are many thousands of feet in the air. I have made some simplex contacts, generally with people only a mile away on the highway or people up on Pikes Peak.

I am planning on replacing it with a better antenna soon, since the trunk mounted location on a low car doesn’t have any clearance issues. For my future 4x4 build though, clearance is a big issue, especially if I end up with a tall vehicle like a 4runner or an Xterra (tall compared to an XJ Cherokee). For that vehicle, my comms requirements are short distance (trail comms), and general repeater usage.

So if the Compactenna performs as well as my 2m/70cm, I would be pleased.

However I lack a way currently to do a real test beyond the analyzer and the “i talked to a couple guys on a repeater” thing. I could do a rough test with a field strength meter, a large valley or some very very open praire someplace would make a half-assed far field range. I would only have a cut from the elevation that I can stand at, but it would give some idea on the antenna’s pattern and efficiency.

why half ass it with an overpriced compromise  ?

just get a 19” 1/4wave NMO

it works fine on 145 and 440

cheap, durable, and affordable

Attached File


Attached File

.
.
keep a larger high gain in the trunk, or truck box for when you need it

@MCSquared

Had the same problem as you. Here is my UHF/VHF antenna setup, works great.

HAM Radio System
YAESU FTM-400XDR HAM Radio (144 / 430 MHz Dual Band C4FM Digital / Analog FM Mobile Transceiver - Improved GPS - 50 Watts)
Diamond K9000LRMO Motorized Antenna Mount
Diamond KRR Mounting Bracket for K9000LRMO
Mini DPTP (On)-Off-(On) Rocker Switch
Diamond NR-770HB Antenna (Bands: 2m/70cm, Gain dBi: 3.0/5.5, Watts: 200, Height: 38.2", Mount: NMO, Element Phasing: 1-1/2l, 2-5/8l, Finish: Black)
Diamond C101Coax Cable Assembly (6.5 Feet RG316 Fits Diamond Mobile Mounts Except K600 SO239 Base PL259 Plug)
ABR Industries LLC 218XATC-PL-18, 18 ft Coax Jumper Cable (UHF PL-259 Male Both Ends LMR-240 RG8X Cable)
UHF-11 Adapter
YAESU MEK-2 Microphone Extension Kit (9.8ft)
RoadPro RP-232 CB Microphone Holder (Black, Plastic)
iKross 2-in-1 Adjustable Swing Extended Cup Mount Holder
Elago Grip Stylus (Black)
SanDisk Ultra 32GB UHS-I/Class 10 Micro SDHC Memory Card

Attached File

Thanks!

Can I get a closeup of the antenna and mounting?  ARF is notoriously unfriendly about compressing photos, and the zoom is never larger than the original.

Also, do they make a triband 2m/1.25m/70cm?  I'll search but I haven't mastered the quick and easy finding of that range of triband antennas  yet.

@MCSquared

Note: the antenna and its mount are separate items from the unit (see my list of items above).

Attached File


Attached File


Attached File


Attached File


Attached File


I used a custom switch to put it up and down; the original one that came with the unit was ugly.

Attached File

Anytime I find myself looking for antenna options, I always seem to end up here

EtA: I appreciate the ease of search and comparison on that site. I have not yet ordered from them so can't say how that goes.

To begin, yes I own the Compactenna and have used it.  Dual band BTW, I believe it's a previous generation as they make them tri-band now.

Whenever you look this antenna up on boards like eham or another, you will get a LOT of negative 'reviews' from people that have never even touched one, much less used one.  Sprinkled in you will find great reviews from people that have used them.

No, I've never put an analyzer on the line or did any formal tests.

I used it on my military M1009 atop an antenna riser with great results.  I added some radials angled steeply downward as is suggested for a fixed location.  I will post pics up after work.

I have also used it on my Grand Cherokee with great results.  The NMO is mounted in the hole where the satellite antenna used to be, which is near the aft hatch.

The only testing I've done is to talk to someone on a fringe repeater, ask them to hold on a second, jump out of the truck and swap on a dual-band whip, then ask if they noticed any difference between the two.  Nobody noticed a difference.

I would not recommend it for your application though, only because it's about a foot tall and has no flex or give whatsoever.  If you don't have the clearance the antenna is going to stop and there will be damage.

EDIT to add: If anyone has the equipment and wants to test it out in a timely manner (not holding onto it for six months) shoot me a PM and I will gladly loan it to you.

Attached File

Attached File

2m/70cm has a bunch of decent antennas so there's not much of a reason to pay a premium for one.

That said, I'd like to try their Ham-8 unit to see how it compares with my Comet UHV-6 or MFJ-1899T. The Comet antenna can be tuned but basically for either the phone part of the band or the CW/Data part of the band but not both. The MFJ antenna has such a microscopically narrow bandwidth that it's almost a single frequency antenna. It would be very interesting to see if the Compactenna works as well or better than the UHV-6 or a Tarheel with a wider bandwidth. Or not.

I've ordered from them years ago.  No issues, but you can find the same antennas cheaper elsewhere.  I think their shipping ended up being a big pricey.  I know the Tram 1180 (decent affordable dual band) can be had for under $25.

I was talking about this to a classmate at the university today, and he had an interesting idea for getting some more elevation when testing an antenna outdoors.

His suggestion was to mount the field strength meter or receiver to a quadcopter, and program the drone to fly around to all the points you want to take a measurement. That way one could take a nice elevation cut instead of just having the azimuth cut from walking around. It would be little more accurate too, since the drone would be using GPS to position itself relative to the radiating antenna.

This still looks time consuming as hell, and expensive, but such an experiment would give a decent idea of the antenna’s pattern and gain. Not as perfect as a real range, but seeing as I don’t have one of those available to me, this idea might be as close as I can get.

Anymore feedback on the Compactenna? I'm looking for options for my truck, as I just purchased an IC-2300H.

https://www.eham.net/reviews/view-product?id=13030
Reviews look good for this device.

That's exactly how one of the original NVIS studies were done in Vietnam, only using a UH-1 instead.

Honestly it'd be better than a real range, as you'd be getting site-specific data that will show the effects of
everything in the environment (ground conductivity, nearby conductors, etc.)